 So let's begin with elbow MR and first let's talk about how these structures look so basically on the medial side there is a single ligament which is called as the medial collateral ligament or the ulnar collateral ligament. This has got an anterior bundle which is the main part, it has got a posterior bundle and it has got a transverse bundle, while imaging on MR the anterior bundle is the main structure that we are evaluating and we can also evaluate the posterior bundle. This transverse bundle we are not really evaluating when we are looking at MR, medially ulnar collateral ligament you may also call it medial collateral ligament, the anterior bundle is the most important and then the posterior bundle like this. Let's look laterally, laterally the anatomy is little more complex, most anterior is the radial collateral ligament. This yellow structure here is the radial collateral ligament, behind that this purple structure is the lateral ulnar collateral ligament or lateral band of ulnar collateral ligament but LUCL is the term used for this purple structure. So you can see it's arising from the humeral epicondyle, lateral epicondyle then it comes posteriorly, it cradles the radial head and goes and attaches here to this supinator eminence of the ulnar out here. This red structure is the annular ligament which is all around the radial head attaching it to the sigmoid notch where the proximal radial ulnar joint is formed. So important radial collateral ligament, lateral ulnar collateral ligament which forms a cradle behind the radial head and neck and then attaches here to the supinator crest along the ulnar. This LUCL is the most important structure in maintaining posterior lateral elbow stability. So this posterior lateral stability is maintained by this LUCL, you can see how it is keeping it in position. Now quick look at the two tendons, biceps and triceps. So biceps we know has a long head arising from the supraglenoid tubercle, short head arising from the coracoid muscles. So these two, they don't really unite, the muscles don't kind of, they kind of remain separate and then it inserts on to the radial tuberosity, the long head has a proximal shorter in smaller insertion, the short head has a distal and larger insertion opposite to what their name suggests. And here you have a Lesser Tess fibrosis which is like a fibrous tissue which is from the distal biceps myotendinous junction covering that and goes over this merges with the fascia which covers this anterior compartment muscle here. So this is Lesser Tess fibrosis, why this is important? If the Lesser Tess fibrosis is also torn along with biceps tendon tear, the biceps tendon will get retracted into the arm. But if the Lesser Tess fibrosis is intact, you may have a tear without the tendon retracting much. So that is the importance. Coming to triceps, you have three heads, long head, lateral head and a medial head. So the importance here is long and lateral head unite together to form a tendinous head which attaches to the olegrenon. The medial head forms a muscular head which attaches to the olegrenon anterior to it. So if you look on the sagittal, you have a tendinous head formed by long and lateral head and anterior to it you have the medial head inserting as a muscular head. And this is the olegrenon. So that is the importance that you can have a tear involving only the tendinous head, you can have a tear involving only the muscular head or involving both. So that anatomy is important. Speaking of elbow is important, it can be done in two ways. One supine patient's arm at his side, but then the body has to be a little oblique because you want to bring the joint to be scanned to the isocenter, the center of the magnet. But if a patient is a little more bulky, this is not a very comfortable position, respiratory movements can get transmitted. So the other thing that can be done is prone, swimmers position with hand completely elevated like that. Now, often it happens that the elbow may be infection deformity, maybe it's in a cast the patient cannot extend the forearm. So then what do we do? It's important that the scan is always angled to the proximal bone. So to the humerus. So along the epicondyles, you draw a line and your cordial should be parallel to that sagittal should be perpendicular. And if a person cannot extend the forearm, you do all sequences like this and one additional cordial, you can take parallel to the radius and allow access. So let's start looking at the anatomy. So we are coming from anterior to posterior. So when I start looking from anterior to posterior, this here would be the bicep standard attaching to the radial tuberosity out here. Now, most anteriorly, I can see a black band, this black linear band out here. That is the radial collateral ligament. So most anterior coming from the humerus to the radial head is the radial collateral ligament. And this is also a good location to look at the radial head, to look at the cartilage along the capitolum and the radial head. As I start going posteriorly, I can now see the bicep tendon insertion onto the radial tuberosity. I can start seeing this ligament here. So now the initial early section is the radial collateral ligament. Now this structure what I'm seeing, I'm drawing around it. This black linear structure is the lateral ulnar collateral ligament. Superficial to it, this whole structure going like this is the common extensor origin. So common extensor origin is the one structure that is involved when somebody has got tennis elbow, a lateral epicondylitis. This may be degenerated, this may be showing tear. This is lateral ulnar collateral ligament that I spoke about. And if I just go posteriorly, I can trace this. So I'm drawing over the ligament. I can trace the LUCL going behind the radial head. Further, I can still see it tracking behind the radial head. And I can see it extending all the way to the supinator crest in the subsequent section. So this what I have outlined from the supinator crest, it comes up this here. You can see this is the lateral ulnar collateral ligament. And then as you come more anteriorly, you can see that it is curving like this and attaching to the humerus. So this is the LUCL. The two structures we looked at most anterior RCL. As you go behind, it is the LUCL. Superficial to it is the common extensor tendon. Okay. Now let's look at the medial structure. So medially the structure that we see prominently is the ulnar collateral ligament or the medial collateral ligament. Towards its humeral attachment, it can have little striated appearance and that is normal. This structure here is the common flexor origin, which would be involved in golfer set. You can have tendonosis, you can have tail. Now, as I go more posteriorly, I can still see the medial collateral ligament or the ulnar collateral ligament. So the anterior bundle and the posterior bundle, we do not really differentiate. We look at all of it from anterior to posterior. This structure here is the ulnar or the medial collateral ligament and superficial to it is the common flexor origin. Okay. Let's start looking at the axial to look for an actor. This is the triceps tendon. Some amount of little striated appearance in that is fine. It's fat and the synomial recesses. You can see the triceps muscle. You can see this brachialis muscle anteriorly and as we come inferiorly, it's very important to look at this structure, which is the ulnar nerve. So always make sure you're looking at the ulnar nerve and this here is the anconious muscle. This is the triceps tendon. Sometimes you may have an accessory muscle. Here you may have an accessory muscle here. In fact, that is a very small one. You may have a more prominent one. Which is anconious epitoclineus. This is the ulnar nerve within the cubital tunnel. So this is the cubital tunnel. Look carefully. Is the ulnar nerve showing normal signal? Is there, is it subluxated or dislocated out of this cubital tunnel? We need to look for that. When I look medially, I start seeing the common flexor origin and as I come slightly inferiorly, this here is the ulnar collateral ligament, the anterior bundle and this portion is the posterior bundle of the ulnar collateral ligament. This is the ulnar nerve and this is the common flexor origin. So these ligaments and tendons are all well seen on the coronal image. So that's why I begin looking at the common ligaments. But after that, I need to compare and look at it on the axial and the sagittal images too. On the lateral side, I start seeing the common extensor origin. Again, it has three parts anteriorly extensor, carpi radialis longus. Then you have extensor, carpi radialis brevis. And the last part is the extensor, digital. So whenever you have tennis elbow, it's ECRB tears, which are common followed by ECRL and when it is more severe, it can affect the extensor digital also. Deep to it, what we see posteriorly is the LUCL and anteriorly is the RCL. So medially, one ligament that is the UCL, laterally anteriorly is RCL, posteriorly is LUCL. Now as we come more inferiorly, I can see the common extensor origin well, I can see the RCL, I can see the LUCL. Further, we can trace these structures inferiorly. So let's keep our eye on the lateral, allocollateral ligament and this here is the allocollateral ligament and more inferior sections. Can you see it going here and inserting onto the supanator crest out here? So this is the LUCL, which cradles the radial head. And here, you can clearly see this dark kind of a C-shaped structure going all around the radial head attaching to this sigmoid notch that is the annular ligament. As we come inferiorly, it's important that our scan includes the bicep tendon insertion onto the radial tuberosity. Sometimes the tech may have stopped the scan higher up. So make sure that the radial tuberosity is always included. Other structures to look at, the radial nerve, this would be the radial nerve and this would be the median nerve location here. So make sure you are looking at the median nerve and the radial nerve as well as the annular nerve. So all the three nerves should be looked carefully. The radial nerve then gives this posterior entraceous branch which goes through the supanator. So we need to look at that also carefully. Next coming to the sagittal images, we are coming from lateral to median. So most lateral, you will start seeing the common extensor origin. As you come inwards, now you can start seeing the radial collateral ligament anteriorly. Posteriorly would be the lateral annular collateral ligament, LUCL. Again on the sag, you can identify it. You can see here, it is coming. You can see this structure here. I'm drawing the arrow pointing to that black. So again, that's the reason non-FATSAT proton density is a best sequence to look for the structures. Yes, you need a FATSAT sequence to look for marrow edema, look for soft tissue edema. So what our protocol for internal derangement is, three plane high resolution proton density image, non-FATSAT. And in elbow, we have two FATSAT, one coronal and one edging. And we also do a coronal gradient because the elbow cartilage is a very thin structure, so it's seen well on gradient. So now FAT acts like a very good contrast. So you can trace this LUCL all the way attaching to the ulna out here. So this here, you can see the LUCL attaching to the ulna. Here, you can see the capitolum very well and see the capitolar cartilage. So you can see the capitolar articular cartilage well. This is a bare area where the circular shape capitolum becomes flat. So that's not a cartilage defect. Look at the radial head also carefully in this location. As I come more medially, I start seeing the triceps tendon. And like I said, some amount of striated appearance is acceptable. This is the triceps tendinous head and this you can see. This is the triceps muscular head, the medial head, which is attached. Okay. Now, you can see this little bit of cartilage fissure or defect like thing out here. I have outlined it on both sides. That's the trochlear ridge. So we should not be calling that as a cartilage defect. That is the trochlear ridge, which is normal. This is the coronoid process. Look very carefully for fractures here. A fracture of the coronoid process, fractures of the radial head, suggests that there has been a posterior dislocation of the elbow. And you have to look very carefully. It will be first the lateral, ulnar collateral ligament, which will be injured. And later with more severe injury, the medial ligament also can be injured. And also important is look at these two notches. This is the coronoid fossa. This is the alecranon fossa. Elbow joint doesn't have too much of space like your knee joint or shoulder joint. So you may not have too much of an effusion, but bodies, conical bodies, or she's bodies may be seen in coronoid fossa or the alecranon fossa. Look carefully at them. And as you come more medially, you can start seeing the ulnar collateral ligament and then the common flexor origin. So sagittal image, you look at these ligaments, but not primary. They are seen well on coronal, corroborated on the axial. So the pitfall, which I said already, is this trochlear ridge. Don't call this a cartilage defect. And this dorsal capital, don't call this cartilage defect. It's because the capital stops here from a circular shape. It becomes flat. So that is normal.